The present invention relates to X-ray camera used in medical diagnosis, dentistry, and the like.
X-ray camera of the kind known heretofore include:
conventional X-ray camera used in medical diagnosis for taking photographs of joint regions such as hands and feet, chest, and so on; and
intraoral X-ray camera and panoramic X-ray camera used in dentistry.
As for the method of displaying images, it has been a general practice to print out X-ray images on films for use as monochrome pictures.
In recent years however, there evolved another method of displaying an image that uses a variety of digital techniques after transferring an X-ray image onto a special fluorescent film.
Some of the techniques proposed for use in the method of displaying images include:
a CR (Computed Radiography) technique, in which a fluorescent image is read by using laser, and stored as a digital image;
a technique, in which a combination of charge coupled device (hereinafter referred to as xe2x80x9cCCDxe2x80x9d) and fluorescent material is used to read directly as a digital image in a similar manner as the video photography; and
a technique, in which a combination of TFT (Thin Film Transistor) panel and photo diode, in combination with fluorescent material is used to read directly as a digital image in a similar manner as the video photography.
Unlike the case of using films, an X-ray camera that uses the digital techniques as above represents a method of expression, in that the equipment accurately reads an X-ray photographic image pixel by pixel, and composes a complete image by realigning again the individual pixel data obtained therefrom on a display device.
For this reason, any defect of pixels of the CCD, the TFT, and the like, manufacturing dispersion of the reading circuits for individual pixels, and so on are reflected just as they are in the pixel data. This has been the failure peculiar to the digital X-ray photography that deteriorates picture quality of display images as typified by slight variations in brightness.
The present invention is to solve the foregoing problem of the prior art technique, and intended to improve picture quality of X-ray photographic images.
To achieve the above-described problem, X-ray camera of this invention comprises:
an X-ray irradiation unit;
an X-ray image sensor;
a controller comprising a correction factor setting unit, a correction factor storage unit, and a correctional operation unit; and
a display unit.
The X-ray image sensor in the above configuration comprises:
a sensor such as CCD, TFT, and the like having a scintillator on a surface of it; and
a substrate having the sensor mounted thereon.
The correction factor setting unit (hereinafter referred to simply as xe2x80x9csetting unitxe2x80x9d) obtains a value La/Ln for an arbitrary pixel xe2x80x9cnxe2x80x9d by dividing a predetermined brightness reference value La set beforehand by a brightness value Ln of the arbitrary pixel xe2x80x9cnxe2x80x9d, and sets the obtained value as a correction factor of each pixel.
The correction factor storage unit (hereinafter referred to simply as xe2x80x9cstorage unitxe2x80x9d) stores the correction factor set by the setting unit.
The correctional operation unit (hereinafter referred to simply as xe2x80x9coperation unitxe2x80x9d) obtains the correction factor from the storage unit, and performs a corrective operation.
The display unit displays an image, which is corrected by the operation unit.
The X-ray camera of this invention, with the configuration as described above, cancels errors in brightness caused by inherent dispersion of the sensors and image detector circuits peculiar to the X-ray camera, by making correction of brightness of the image obtained in the photography, and thereby it can realize substantial improvement in quality of the X-ray image.